1. Field of the Invention
The subject invention generally pertains to vehicle levelers and more specifically to one with a low profile.
2. Description of Related Art
Truck levelers and dock levelers often work in conjunction with each other in docking a truck or trailer to a loading dock platform. A typical truck leveler includes a deck that extends between a vehicle-approach edge that is hinged to the driveway and a rear edge that is adjacent the face of the loading dock. As a truck backs its trailer or itself onto the deck, the deck pivots about the hinge to raise a rear portion of the vehicle so that the bed of the truck or trailer is closer to the height of the loading dock platform. A conventional dock leveler can then make up the remaining height differential and bridge the gap between the dock platform and the trailer bed to allow a forklift access to cargo on the trailer.
A typical dock leveler usually includes its own deck that has one edge pivotally coupled to the dock platform. The pivotal motion adjusts the height of an opposite, distal edge of the dock leveler""s deck to roughly match the height of the truck""s rear edge. A lip extension pivots outward from the distal edge of the dock leveler""s deck to bridge the gap between the dock platform and the rear of the truck.
Newer model trucks and trailer beds continue to get lower to the ground, while existing dock heights remain at a fairly standard height of about 48 inches. This increases the need for truck levelers, as many conventional dock levelers alone are unable to effectively make up the ever increasing height differential. In some cases, the truck may be so low that the height differential may be beyond the travel limits of the dock leveler. In other cases, a conventional dock leveler must descend to create a ramp so steep that a forklift can no longer make the grade to get off the trailer and back onto the dock.
One solution has been to have longer dock levelers to minimize the angle created by the leveler. Such a solution, however, may not be desirable as it consume valuable floor space in loading dock areas that are typically congested.
A second solution is to have a conventional truck leveler raise the rear of the vehicle so that its bed more closely matches the height of the dock. However, raising the bed of a fully loaded trailer (plus the weight of a forklift) requires a leveler of substantial strength and rigidity. With current truck levelers, the strength and rigidity is achieved simply by adding reinforcing beams underneath the upper traffic surface of the leveler""s deck. But the resulting added thickness of such a leveler creates some problems.
For example, although a conventional truck leveler may work well for lower trailer beds, a truck with a standard, higher bed on a relatively thick truck leveler may now end up too high. The dock leveler might not be able effectively reach up to the top edge of the elevated trailer bed, or a vehicle restraint (e.g., the type disclosed in U.S. Pat. No. 4,264,259) associated with the loading dock might not have enough upward travel to reach the truck""s ICC bar. These problems can occur even if the truck leveler is left in its lowered position. Moreover, a relatively thick leveler can also create a significant obstruction over which a truck must drive, which can be a problem for both high and low truck/trailer beds.
To minimize the elevation of the upper traffic surface of a truck leveler, a leveler can be installed in a pit to place the traffic surface of the leveler generally flush with the driveway approach. However, such a pit is not only expensive, but can also create a reservoir in which water and debris can accumulate. The water may not only promote corrosion of the leveler, but the leveler may lockup entirely if the water freezes to it. Removing debris from underneath a truck leveler set in a pit becomes an unpleasant chore that is often neglected. This is due to the difficulty of reaching underneath a relatively expansive deck that may only rise a few inches for limited access.
Some truck levelers include a power wheel chock that prevents the truck from accidentally rolling away from the dock. To release the truck, the chock retracts below the drive-on surface of the leveler. Providing room for a retracted chock underneath the leveler can also make a truck leveler thicker, which can thus create all the problems already mentioned.
In order to provide a strong truck leveler that can accommodate a retractable wheel restraint while minimizing the height of the leveler""s upper traffic surface, a pivotally mountable leveler is provided that includes two lateral beams that extend above the traffic surface.
In some embodiments, a track-mounted wheel restraint is added to the leveler with the track disposed above the leveler""s upper traffic surface to provide the leveler with added strength and rigidity without increasing the height of the traffic surface unnecessarily.
In some embodiments, the leveler""s deck includes a central joint to avoid having to transport and install one excessively large deck.
In some embodiments, a central beam is added to connect the central joint and add strength and rigidity to the leveler. The central beam can extend above the upper traffic surface to minimize the height of the traffic surface.
In some embodiments, the central beam includes an upper member, such as a flange or plate, that is displaced above the traffic surface to define an air gap between the two, thus creating a stronger beam with a minimal amount of material.
In some embodiments, a rear beam is disposed above the upper traffic surface to provide the traffic surface with strength and rigidity while minimizing the height of the surface.
In some embodiments, a wheel guide is provided to help keep the vehicle properly positioned on the upper traffic surface and/or to keep a vehicle from running up against the side of a wheel restraint that may be mounted on the traffic surface.
In some embodiments, a lift cylinder for a truck leveler is provided with a trunnion mount at an intermediate position along the length of the cylinder.